China last week enacted the sweeping security law for the restive city of around 7.5 million people, banning acts of subversion, secession, terrorism and collusion with foreign forces.
The legislation, which has sent a wave of fear through the territory, has criminalized dissenting opinions such as calls for independence or autonomy.
Digital rights group ProPrivacy called Facebook’s move “a win for both digital privacy and human rights in the region.”
“With the stakes so high, and the punishments so severe, it is great news to see big tech companies like WhatsApp pushing back in favor of democracy and freedom of expression,” the group said.
However it noted the move could lead to WhatsApp being blocked in Hong Kong as it has been in mainland China.